Draft regulator



July 28, 1942. BAWMANN 2,291,018

7 DRAFT REGULATOR Filed May 16, 1939 2 Sheets-Sheet l m T 0 .N. Mm Mn 11W. A

July 28, 1942. F. BACHMANN DRAE-T REGULATOR Filed May 16, 1939 2 Sheets-Sheet. 2 y- I v INVENTOR Freak Each/770m? 60no7,0d4ny, B Q1? ATTORNEYS Patented July 28, 1942 UNETED STATES PATENT OFFICE 2 Claims.

This invention relates to draft regulators, particularly to draft regulators for the pipes or stacks taking the exhaust gases of combustion furnaces, and has for an object the provision of improvements in this art.

Often a stack, chimney or pipe for the exhaust gases of combustion furnaces may have a draft which is too strong for immediate conditions, though needed for forced fire conditions. Under such conditions it is common to introduce additional make-up air into the stack beyond the combustion chamber of the furnace to reduce the draft through the furnace. Many furnaces are provided with auxiliary inlets and dampers to control the draft in this way.

Herein an auxiliary inlet for make-up air is provided but in the present case the inlet control mechanism is of a novel type adapted to operate automatically in accordance with intake demands or fluctuating conditions of induced draft rather than in accordance with temperature conditions as is now common. It is also adjustable for different demands and this adjustment may be made in a simple and easy manner. It has been found that the use of this inlet control mechanism gives a very noticeable economy in fuel because of its more ready response to the needs of the system. While the invention will be described herein with particular reference to use for make-up air inlets for furnaces, it will be obvious that it may be used to advantage for many other purposes.

An exemplary embodiment of the invention will now be described for purposes of illustration, reference being made to the accompanying drawings thereof, wherein:

Fig. l is a side elevation of the device installed in an auxiliary air inlet pipe such as that shown in Fig. 8;

Fig. 2 is a horizontal section partly in elevation, taken on the line 2-2 of Fig. 1;

Fig. 3 is a partial enlarged section taken on the line 3-3 of Fig. 2;

Fig. 4 is a partial side elevation looking at the left side of Figs. 1 and 2;

Fig. 5 is an enlarged view of the central portion of Fig. 2;

Fig. 6 is a vertical section taken on the line 66 of Fig. 1 showing the counterweights in outer adjusted position and the damper in closed position;

Fig. '7 is a view similar to Fig. 6 but showing the counterweights in inner adjusted position and the damper in open position;

Fig. 8 is a plan view of a furnace and stack installation embodying the device shown in Figs.

Fig. 9 is a partial vertical section of a modification.

Referring to Fig. 8, an installation adapted to use this invention is shown. It comprises a furnace ID, a flue pipe H, a chimney l2, and an auxiliary inlet pipe l3 for make-up air. A damper is provided for the inlet [3. This is indicated in Fig. 8 and shown in detail in Figs. 1 to 7. The damper plate is referred to by the numeral l4.

The damper plate I4 is mounted on journals l5 to turn about a horizontal axis. The journals vmay be secured by set screws I6 to brackets I! carried by the plate l4. The journals rotate in bearings 18 secured to the inlet pipe l3.

The axis of the journals I5 is located above the center of the plate to provide a greater area on one side than the other whereby suction on the greater area may open the damper as desired. Further to assist this action, a baffle plate I9 is secured in the pipe in front of the upper or smaller area of the plate 14. The baffle I9 reduces the effective suction area on the upper portion of the plate l4, especially when the plate is closed, and this produces easier opening, particularly in pipes where there is a greater natural draft at the top than at the bottom. The area of the baflle plate is large relative to the area of the damper plate above the hinge line.

The damper plate 14 is made smaller than the inside of the inlet pipe l3 to permit easy operation and provide an annular space 20 for a steady inflow of air. This predetermined inflow may be of any desired amount. One benefit derived from such a steady inflow is the avoidance of jerky operation of the plate. In a round pipe the hinge axis of the plate cannot be too high above the geometric center or the plate will bind when it swings up, even when the clearance space 20 is of considerable size. If the hinge axis is not too high a quicker action of the plate is permitted than would otherwise be the case.

One or more circumferentially spaced stops 2| serve to limit the outward movement of the lower portion of the plate l4.

Means are provided for varying the action and changing the initial position of the damper l4. Part of these means comprises a weight 22 attached to an arm 23 carried by one of the journals 15. The value of the Weight and its position along the arm may be adjusted as desired. The arm 23 may also be operated by pressure regulating devices or in connection with other draft regulators, particularly for coal burning installations. The other part of such means may comprise balance weights 24 carried by arms 25 mounted on pivot pins 25 secured in a bracket 21 attached near the center of the plate. The hubs of the arms 25 may be provided with notches 28 adapted to cooperate with set screws 29 carried by anchors 30 to hold the arms in various adjusted positions. When the weights 24 and arms '25 are swung inward, as shown in full lines in Fig. 2, the center of gravity lies substantially in a vertical plane passing through the axis of the journals l5 and the weights have practically no effect on the plate. But when the weights 24 are moved outward, as shown in dotted lines in Fig. 2, the plate is urgedcormterclockwise toward closed position, as viewed in Figs. 6 and 7. The weights 24 are spherical on one side but fiat on the other so as to fit fiat against the plate. Either one or both weights may be swung out ata time, thus giving a very wide range of adjustment values. V

When the weights are symmetrically hinged and swung in a plane or planes perpendicular to the damper plate the weight on the'bearings may be kept reasonably well balanced and this makes for very easy operation of the plate. It will be noted that applicant has mounted the plate so that it is held equally at all times between its bearings and has provided roller bearings so that it will move with the greatest ease. With this mounting in which the weights are nicely balanced symmetrically with respect to the bearings, the plate may be moved at the lightest touch and never tends to become stuck in any position. This is a matter of importance in avoiding jerky and inaccurate action of the damper.

Means are provided for maintaining the bafiie plate in central position, the means shown in Fig. 3, comprising an enlarged portion 3| on the journals Hi to form shoulders cooperating with the ends of bearings 32. K

In Fig. 9 there is shown a modified form in which one or a plurality of threaded bolts 35 are provided for shifting the balance of weight from one side of the damper plate to the other. This may be used in place of or in addition to the weights 22 and 24. The device otherwise may be the same as the previous form. In Fig. 9 the plate l4 and its journals l5 are shown.

When the adjustable weights. 24 are used on the damper plate it is not always necessary to use the weight 22 and the arm 23, the weights on their arms providing adjustable balance for the draft exerted on the lower edge of the damper plate. Also while two weights 24 are shown and provide better distribution of weight on the bearings, it may sometimes be preferable to have only one weight. In any event the two weights are independent and may be separately adjusted.

The operation of the device will be apparent from the-foregoing description. 'It is to be understood that the invention may have various embodiments within the limits of the prior art and the scope of the subjoined claims.

I claim:

1. A draft regulator for auxiliary make-up air inlet pipes, comprising in combination, an inlet pipe, a damper plate therein hinged between its upper and lower edges above and parallel to its horizontal center line to permit its larger side at the bottom to swing inward under suction, and a 'baflle plate in the upper part of said pipe fitting against the upper side of the damper plate when closed, said bafile plate being of considerable size relative to the area of the upper part of the damper plate to effectively reduce the suction thereon, particularly when closed.

2. Apparatus as set forth in claim 1 in which the lower edge of said bafiie plate is defined by a chord parallel to the axis of said damper plate and the horizontal center line of said pipe.

FRANK BACHMANN. 

